Scientists in Japan said on Wednesday they have created teeth -- complete with connective fibers and bones -- by using mouse stem cells and successfully transplanted them into mice, a step they hope will lead to progress in stem cell research. The entire tooth units, which were inserted into lower jaws of mice, attached successfully with jaw bones and the rats were able to chew normally, the researchers wrote in a paper in PLoS One (Public Library of Science). "The bioengineered teeth were fully functional ... there was no trouble (with) biting and eating food after transplantation," wrote Masamitsu Oshima, assistant professor at the Research Institute for Science and Technology, Tokyo University of Science.